The use of mechanical apparatus for gathering a bundle of brush bristles and forming a tuft is well known in the brush making art. For example, U.S. Pat. No. 1,512,588 shows a conventional brush bristle gathering and tuft forming head, known in the art as a "filling tool." Filling tools typically are adapted as components of machines for the complete manufacture of entire brush assemblies, such as the conventional "drill and fill" machines of the type shown in U.S. Pat. Nos. 2,324,480 and 3,704,915.
The conventional brush bristle gathering, tuft forming, and tuft inserting ("filling") operation includes the separate steps of (1) gathering ("picking off") a plurality of brush bristles (a bundle) from a stock box or magazine and delivering the bundle to the tuft forming area, (2) forming and positioning a fastener such as a wire staple or the like at the central portion ("mid-point") of the bundle, (3) forming a "tuft" of bristles by bending or "breaking" the bundle at its mid-point, and (4) driving the fastener and broken portion or "bight" of the bundle into a brush block workpiece whereby the fastener anchors the resulting bight portion of the bundle to the block with the two end portions or legs of the bundle extending outwardly to provide the bristle tuft.
In the conventional brush filling tool apparatus, several separate sub-assemblies are necessary to perform the steps of the conventional brush filling method. For example, one sub-assembly (a "picker bar") gathers the bristle bundle from a stock box or magazine and transports the bundle to the tuft forming area. Conventional picker bars are illustrated in FIGS. 10 and 11. Another sub-assembly forms a fastener and an additional subassembly positions the fastener around the mid-point of the bundle. A further sub-assembly forms the tuft by breaking the bundle at its mid-point and yet another sub-assembly anchors the fastener/tuft combination to the brush block workpiece.
Each of the filling tool sub-assemblies requires a complicated precision drive mechanism necessary to cause the brush filling tool apparatus to operate in a synchronous manner to form and anchor a multiplicity of brush tufts to brush block workpieces at a high production rate on the order of several hundred cycles per minute. In particular, the picker bar sub-assembly includes a complicated precision drive mechanism necessary to cause the picker bar to operate in a synchronous manner with the filling tool. In addition, the sub-assemblies for forming and positioning the fastener at the mid-point of the bristle bundle also include complicated precision drive mechanisms. The interaction timing between these separate drive mechanisms is critical and requires constant monitoring and adjustment. Thus these complicated mechanisms and filling tool sub-assemblies are difficult to maintain due to their multiplicity of moving parts, are prone to mechanical wear and vibration, and fail frequently resulting in costly down-time for the brush manufacturing machinery.
In addition, each sub-assembly corresponds to a separate step necessary in the conventional brush filling method. During execution of the conventional filling operation, each filling tool sub-assembly advances while performing its separate step and then reciprocates in relation to the other sub-assemblies which remain stationary or counter-reciprocate. Thus, the operation each subassembly of the filling tool requires a discrete time period in the complete filling tool operation cycle. The necessity of these discrete time periods extends the time required for one complete filling cycle and contributes to the inefficiency of the conventional brush tuft gathering and forming method.